The present disclosure refers to turbomachines. More specifically, the disclosure relates to improvements concerning sealing devices suitable for separating adjacent compartments in a turbomachine, such as a turbomachine which processes a wet gas, i.e. a gaseous flow containing liquid particles and/or solid particles.
In many industries, specifically but not exclusively in oil and gas extraction and processing industry, turbomachines are used, which process a gas that can contain solid or liquid particles entrained in the main gaseous flow processed through the turbomachine. Subsea compressors are typical examples of turbomachines which process a wet gas, as gaseous hydrocarbons extracted from a gas field often contain heavier hydrocarbons in the form of liquid droplets and/or solid matters dragged by the gas flowing through the turbomachine.
Turbomachines contain elements which are particularly sensitive to solid and/or liquid particles. Typical components which must be protected against the penetration of solid and/or liquid matter in a turbomachine, such as a centrifugal compressor, include, but are not limited to, active magnetic bearings, oil bearings, electric motors and the like. Typically, such components can be integrated in a turbomachine casing, e.g. in a compartment, which is separated by a compartment housing the compressor impellers and wherein wet gas is processed.
Sealing arrangements and devices are usually provided to separate a first compartment containing the compressor from adjacent compartments containing contaminant-sensitive components, such as bearing and electric motors. In some known embodiments buffer seals are used for isolating a compartment containing one or more contaminant-sensitive components from a compartment containing the compressor, and more specifically the compressor impellers through which contaminated gas, i.e. gas containing contaminants in the form of liquid and/or solid particles, is processed.
Dry gas is delivered to the buffer seals to generate a gas barrier between the two compartments, aimed at preventing the ingress of contaminants from the compressor compartment, or the compartment housing the compressor impellers, into the protected compartments containing the contaminant-sensitive component(s) of the compressor.
Dry gas is sometimes provided from an external source of clean gas. Particularly in off-shore installations providing a source of clean dry gas is a costly exercise, since no such source is available near the off-shore installation. Systems have therefore been developed, which use the same gas processed by the compressor to provide dry gas to the buffer seals. Gas is extracted from the compressor, cleaned and conditioned in a dry gas skid or the like and subsequently delivered to the buffer seals.
In spite of the efforts devoted to the improvement of buffer seals or dry gas seals, there is still a constant need for further improving the sealing efficiency of such devices.